Hoisting mechanism



Feb. 23, 1932.

J. R. MCGIFFERT 1,846,429.

HOISTING MECHANISM Filed Nov. 7, 1929 3 Sheets-Sheet l INVENTOR.

N M KWFGi/fm-z 1- via? ATTORNEYS.

m). 23, 1932; R McGlFFERT HOISTING MECHANISM Filed Nov. 7, 1929 3 Sheets-Sheet INVENTOR. cJfiH 75 7% 6777272 ATTORNEYS,

Feb. 33, i932.

J- R. M GIF'FERT HOISTING MECHANISM Filed Nov. 7, 1929 3 Sheets-Sheet 5 INVENTOR.

I ATTORNEY5.

Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE JOHN B. MCG'IFFELRTT, F DULUTH, MINNESOTA, ASSIGNOR TO GLYDE IRON WORKS, OF DULUTH, MINNESOTA, A CORPORATION OF MAINE HOISTING MECHANISM Application filed November 7, 1929. Serial No. 405,454.

type of hoisting mechanism used for the purpose of elevating building material and the like to the upper levels of a building being constructed, the cable by which the elevator carriage is lifted and lowered is wound upon a spool forming a part of the hoisting mechanism. In the type of hoists now commonly employed the elevator carriage or the material which is being hoisted is held in suspended position by simply disconnecting the driving means from the spool and then applying a brake to a drum in association with such spool and the load is thus held in elevated position by the operator maintaining the brake in engagement with the brake drum, either by a hand lever or the common V type of foot pedal. In this typeof construction the brake which is employed to maintain the load or carriage in elevated position is likewise utilized to gradually lower the car riage or suspended load to the ground.

Due to the fact that the operatorscom-i monly employed in connection with hoisting mechanism are naturally apt to be somewhat careless in the manner in which the hoisting mechanism is operated, and even if a most careful operator were employed, there are numerous possibilities of the operators foot being lifted or otherwise removed from the brake pedal while the load or suspended ma- 5 terial is in elevated position. In the common type of construction, any accidental disengagement of the brake which holds the car riage or load in suspended position will permit such load to drop with great force and endanger the lives of workmen or others in the immediate vicinity of the material being hoisted. 7

My invention provides a means whereby such accidental dropping of the suspended load is absolutely obviated and the efficiency of the hoisting mechanism in no way impaired. A device which will prevent the ac-.

cidental dropping of the suspended load must of necess1ty act instantaneous with the accidental release of the manually controlled brake, since an appreciable delay would permit the suspended material to gainsufiicient momentum to cause substantial damage to the entire hoisting mechanism if the safety brake .would not operate until such momentum had been established.

It is an object of my invention to provide a means whereby the load suspended by a hoisting mechanism cannot be accidentally dropped. A further object of my invention is to provide a means whereby the safety brake operates instantaneously with the release of the manually controlled brake. A further object of my invention is to provide a safety brake whereby the operation of such brake is entirely automatic. Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims; the annexed drawings and the following de scription setting forth in detail certain mechanism embodying the invention such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In said annexed drawings Fig. 1 is a plan View of a hoisting mechanism embodying the principles of my invention; Fig. 2 is a side elevation of the mechanism illustrated in Fig. 1; Fig. 3 is a fragmentary plan view of the safety brake actuating mechanism; Fig. 4 is a part sectional, part elevational view of the service brakes and associated actuated mechanism; and Fig. 5 is a part sectional, part elevational view of the safety brakes and their associated mechanism.

Referring more specifically to the drawings and more especially to Fig. 1, the hoisting mechanism here shown is of the common type and consists of side frame members 1, end frame members 2 and cross sills 3 and 4, upon which the operating mechanism is mounted. The hoist here shown has winding spools 5 and 6 which are co-axially mounted with the gear wheels 7 and .8, respectively, which run in mesh with a pinion 9 rigidly mounted on a shaft 10 which terminally carries a driving wheel 11 receiving its rotation from the sheave 12 through the flexible driving means 13. The winding spools 5 and 6 are respectively caused to rotate upon rotation of the levers 14 and 15, respectively, which act through thrust screws to bring the opposite ends of the spools 5 and 6 in contact with friction blocks carried by the gear Wheels -7 and 8. This is acombrakes by which the rotation "ofthe spools 5 and 6 is normally controlled; The brake band has its one terminal portion 22 rigidly secured to the plate members 23 and 24 by means of the pin 25 passing through the looped end of such terminal portion 22, which pin of course is readily removable to permit replacement of the brake bands,

should they become worn or otherwise incapacitated. The other end 26 of the brake band 20 is pivotally secured to a member 27 by means of the pin 28. This member 27 is rigidly mounted on the shaft 29 which is journaled in the bearings 30, 31 and 32 pro- 'vided therefor, which are rigidly secured to "the members 1 and 3, respectively. .The shaft 29 has rigidly mounted thereon a lever 33 by 'means of the bolt 34 passing through the bi-' furcated end 35 of the lever 33 which closely hugs the shaft 29. The lever 33has secured thereto a plate 36 which is in the form of a pad adapted to receive thefoot of the operator.

Mounted on the brake drum 18 is a safety brake band 37 which has its terminal .portions connected to the pivotal member 38 which is supported by the pin 39 passing through the rigid plates 23 and 24. The pin 39a, by which the end 40 of the brake band 37 is connected to the pivotal member 38, is nearer the axis of rotation of the pivotal member 38 than the pin 41, to which is connected the end 42 of the brake band 37. The pivotal member 38 has a terminal portion thereof pivotally connected to the link 43 by means of thepin 44. The link 43 is in turn pivotally connected to the member 45 by means of the pin 46, which member 45 is a part of the member 27. The pin 44 also secures the end of the rod 47 which extends 7 through the aperture 48 in the sill 3 and which has co-axially mounted thereon a .spring 49 which is secured to the rod 47 by means of the nuts 50 and the washer 51.

The construction and arrangement of the varlous members comprislng the service and safety brakes 21 and 52, respectively, which are mounted on the drums 17 and 19, is somewhat different from the construction and arrangement of the parts just described, in order to bring the operating levers 33 and 53 in juxtaposition in orderto facilitate the control of both spools by the'operator standing in one position. It will be seen, however, that the operation of the pivotal member 54 and the various operating parts of this drum, which have been given primed ordinals corresponding to the ordinals used in describing the parts associated with the other drum, is identical and the same results are accomplished.

The brake bands 7 on the various brake drums have lugs 55 associated therewith. which receive the adjusting screws 56 by which the various brake bands may be adjusted to compensate for wear. It'should' also be notedthat the brake band will be faced with a suitable lining for the purpose of increasing the efficiency as well as lengthening the life of the bands.

In theoperation of this mechanism the di-' rection of rotation of the drums necessary to wind the cable thereon is indicated by the arrows on Fig. 2. The spring 49 which causes the rod 47 to be moved to the left, as shown in.

Fig. 2, maintains the safety brake 37 in en gagement with the brake drum 18 as well as the lever 33 in the elevated position. When the spool 5 is rotated in the direction indicated by the arrow in Fig.2, that is the direction in which the cable is wound on the spool, the brake drum 18 will drag the safety brake with it and the end 42 of this brake will cause a counter clockwise rotation of the pivotal member 38, thereby releasing the safety brake and preventing its interference with the ro-" tation of the spool 5. If, however, the spool 5 attempts to rotate in a clockwise direction the spring 49 which holds the safety brake in engagement with the brake drum 18, along with the torque exerted by the end 40 of the safety brake, will cause this brake to rigidly grip the brake drum 18 and prevent the spool 5 from rotating to unwind the cable. It will be seen that the greater the tangential force;

the safetybrake exertedby the cable on the spool 5, the greater rotate the shaft 29 in a clockwise direction 2 foot accidentally slip off the plate 36 or otherwise be removed therefrom, the member 33 would instantly be elevated due to the action of the spring 49 and the service brake would be simultaneously applied before the descending load has had opportunity to gain any appreciable momentum in its descent.

It will be seen from an examination of the above described mechanism that there is no possibility of accidental dropping of a suspended load when this type of mechanism is employed. Not only is the possibility of an accidental dropping of the load entirely obviated, but the safety brake is absolutely positive in its operation and no mental lapse on the part of the operator can in any way prevent its functioning. Also, the safety brake as constructed, is instantaneous in its operation and accomplishes the desired result without in any way subjecting the hoisting mechanism to undue shocks or strains set upbya rapidly dropping load.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and d1stinctly claim as my invention 1-- 1. In a hoisting mechanism, the comblnation of a winding spool, a manually operated brake for controlling the rotation of said spool, and a. safety brake for automatically arresting the rotation of said spool in a single direction when said manually operated brake is fully released.

2. In a hoisting mechanism, the combination of a winding spool; a service brake for said spool; a safety brake for said spool; and means for actuating said service brake, said actuating means adapted to sustain said safety brake in non-operable relation to said spool when said service brake is in operable relation thereto.

3. In a hoisting mechanism, the combination of a winding spool, means for revolubly driving said spool, brake drums associated with said spool, a service brake mounted on one of said spools, a safety brake mounted on the other of said spools, and means for clamping said service brake on its associated drum, said clamping means adapted to disengage said safety brake immediately prior to and during the application of said service brake.

In a hoisting mechanism, the combination of a winding spool, means for rotating said spool, brake drums associated with said spools, a service brake mounted on one of said drums, a safety brake mounted on another of said drums, one end of said service brake rigidly mounted, the other end of said service brake mounted on a movable member,

pivotally supported means for securing the ends of said safety brake, and means connecting said movable member with said pivotally supported member for releasing said safety brake as said service brake is applied.

5. In a hoisting mechanism, the comb-ination of a winding spool; means for rotating .said spool; brake drums associated with said spool; a service brake mounted on one of said brake drums; a safety brake mounted on an other of said brake drums; one end of said service brake rigidly mounted; the other end of said service brake mounted on a movable member; pivotally supported means for securing the ends of said safety brake, one end thereof being mounted nearer the axis of rotation of said pivotally supported means than the other end; and means connecting said movable member with said pivotally supported member for releasing'said safety brake as said service brake is applied.

6. In a hoisting mechanism, the combination of a winding spool; means for rotating said spool; brake drums associated with said spool; a service brake mounted on one of said brake drums; a safety brake mounted on an other of said brake drums; one end of said service brake rigidly mounted; the other end of said service brake mounted on a movable member; pivotally supported means for securing the ends of said safety brake, one end thereof being mounted nearer the axis of rotation of said pivotally supported means than the other end; resilient means for maintaining said safety brake mechanism and said service brake mechanism for releasing said safety brake as said service brake is applied.

igned by me, this 4th day of November,

JOHN R. MQGIFFERT. 

